#include <math.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>
#include <limits.h>
#include <stdbool.h>
int maximum(int count1,int count2)
    {
    if(count1>=count2)
        return count1;
    else 
        return count2;
}
int main(){
    int n; 
    scanf("%d",&n);
    int *a = malloc(sizeof(int) * n);
    for(int a_i = 0; a_i < n; a_i++){
       scanf("%d",&a[a_i]);
    }
    int max=0,i;
    for(i=0;i<n;i++)
        {
         int temp=a[i];
        int j;
        int count1=0,count2=0;
        for(j=0;j<n;j++)
            {  int var=temp-a[j];
            if(var<2 && var>-1)
                { 
                count1++;
               // printf("%d %d %d count1\n",count1,temp,a[j]);
            }
            if(var>-2 && var<1)
                {
                count2++;
                // printf("%d %d %d count2\n",count1,temp,a[j]);
            }
        }
        int count=maximum(count1,count2);
        if(count>max)
           max=count;
    }
    printf("%d",max);
    return 0;
}